The 5:2 diet (the Fast Diet)
This is a relatively new one which took the world by storm a couple of years ago. Basically with this plan , you eat a very very low-calorie diet (500 cals for women, 600 for men) for two days a week and can eat what you like the rest of the time.
If you have an active social life which involves a lot of eating out, this might well be for you as you only have to diet two days a week. If you are a snacker, and tend to yearn for chocolate and crisps in between meals, the chances are you'll be eating too much in your non-dieting days for this to work.